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Sasaki S, Yamagishi A, Yoshimura Y, Enya K, Miyakawa A, Ohno S, Fujita K, Usui T, Limaye S. In situ bio/chemical characterization of Venus cloud particles using Life-signature Detection Microscope for Venus (Venus LDM). Can J Microbiol 2022; 68:413-425. [PMID: 35235433 DOI: 10.1139/cjm-2021-0140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Much of the information about the size and shape of aerosols forming haze and the cloud layer of Venus is obtained from indirect inferences from nephelometers on probes and from analysis of the variation of polarization with the phase angle and the glory feature from images of Venus. Microscopic imaging of Venus' aerosols has been advocated recently. Direct measurements from a fluorescence microscope can provide information on the morphology, density, and biochemical characteristics of the particles; thus, the fluorescence microscope is attractive for the in situ particle characterization of Venus' cloud layer. Fluorescence imaging of Venus' cloud particles presents several challenges due to the sulfuric acid composition and the corrosive effects. In this article, we identify the challenges and describe our approach to overcoming them for a fluorescence microscope based on an in situ bio/chemical and physical characterization instrument for use in the clouds of Venus from a suitable aerial platform. We report that a pH adjustment using alkali was effective for obtaining fluorescence images, and that fluorescence attenuation was observed after the adjustment, even when the acidophile suspension in the concentrated sulfuric acid was used as a sample.
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Affiliation(s)
- Satoshi Sasaki
- Tokyo University of Technology, 13097, Hachioji, Japan, 192-0914;
| | - Akihiko Yamagishi
- Tokyo University of Pharmacy and Life Sciences, 13115, Hachioji, Tokyo, Japan;
| | | | - Keigo Enya
- JAXA, 13557, Sagamihara, Kanagawa, Japan;
| | - Atsuo Miyakawa
- Tokyo University of Pharmacy and Life Sciences, 13115, Hachioji, Tokyo, Japan;
| | - Sohsuke Ohno
- Chiba Institute of Technology, 12829, Chiba, Chiba, Japan;
| | | | | | - Sanjay Limaye
- University of Wisconsin-Madison, 5228, Madison, Wisconsin, United States;
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Venus’ Cloud-Tracked Winds Using Ground- and Space-Based Observations with TNG/NICS and VEx/VIRTIS. ATMOSPHERE 2022. [DOI: 10.3390/atmos13020337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Characterizing the wind speeds of Venus and their variability at multiple vertical levels is essential for a better understanding of the atmospheric superrotation, constraining the role of large-scale planetary waves in the maintenance of this superrotation, and in studying how the wind field affects clouds’ distribution. Here, we present cloud-tracked wind results of the Venus nightside, obtained with unprecedented quality using ground-based observations during July 2012 with the near-infrared camera and spectrograph (NICS) of the Telescopio Nazionale Galileo (TNG) in La Palma. These observations were performed during 3 consecutive days for periods of 2.5 h starting just before dawn, sensing the nightside lower clouds of Venus close to 48 km of altitude with images taken at continuum K filter at 2.28 μm. Our observations cover a period of time when ESA’s Venus Express was not able to observe these deeper clouds of Venus due to a failure in the infrared channel of its imaging spectrometer, VIRTIS-M, and the dates were chosen to coordinate these ground-based observations with Venus Express’ observations of the dayside cloud tops (at about 70 km) with images at 380 nm acquired with the imaging spectrometer VIRTIS-M. Thanks to the quality and spatial resolution of TNG/NICS images and the use of an accurate technique of template matching to perform cloud tracking, we present the most detailed and complete profile of wind speeds ever performed using ground-based observations of Venus. The vertical shear of the wind was also obtained for the first time, obtained by the combination of ground-based and space-based observations, during the Venus Express mission since the year 2008, when the infrared channel of VIRTIS-M stopped working. Our observations exhibit day-to-day changes in the nightside lower clouds, the probable manifestation of the cloud discontinuity, no relevant variations in the zonal winds, and an accurate characterization of their decay towards the poles, along with the meridional circulation. Finally, we also present the latitudinal profiles of zonal winds, meridional winds, and vertical shear of the zonal wind between the upper clouds’ top and lower clouds, confirming previous findings by Venus Express.
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Milojevic T, Treiman AH, Limaye SS. Phosphorus in the Clouds of Venus: Potential for Bioavailability. ASTROBIOLOGY 2021; 21:1250-1263. [PMID: 34342520 DOI: 10.1089/ast.2020.2267] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Aerosol phase elements such as phosphorus (P), sulfur (S), and metals including iron (Fe) are essential nutrients that could help sustain potential biodiversity in the cloud deck of Venus. While the presence of S and Fe in the venusian cloud deck has been broadly discussed (Zasova et al., 1981; Krasnopolsky, 2012, 2013, 2016, 2017; Markiewicz et al., 2014), less attention has been given to the presence of P in the aerosols and its involvement in the multiphase chemistry of venusian clouds and potential sources of P deposition in the venusian atmosphere. A detailed characterization of phosphorus atmospheric chemistry in the cloud deck of Venus is crucial for understanding its solubility and bioavailability for potential venusian cloud microbiota (Schulze-Makuch et al., 2004; Grinspoon and Bullock, 2007; Limaye et al., 2018). We summarize our current understanding of the presence of P in the clouds of Venus and its role in a hypothetical atmospheric (bio)chemical cycle. The results of the VeGa lander measurements are put into perspective with regard to nutrient limitation for a potential biosphere in venusian clouds. Our work combines the results of the VeGa measurements and focuses on P as an inorganic nutrient component and its potential sources and chemical behavior as part of multiple transformations of atmospheric chemistry. The VeGa data indicate that a plentiful phosphorus layer exists within a layer that reaches into the lower venusian clouds and exceeds minimum P abundances for terrestrial microbial life. Extreme acidification of airborne phases in the atmosphere of Venus may facilitate P solubilization and its bioavailability for a potential ecosystem in venusian clouds. Further sampling and P abundance measurements in the atmosphere of Venus would improve our knowledge of P speciation and facilitate determination of a bioavailable fraction of P detected in venusian clouds. The previous results deserve further experimental and modeling analyses to diminish uncertainties and understand the rates of atmospheric deposition of P and its role in a potential venusian cloud ecosystem.
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Affiliation(s)
- Tetyana Milojevic
- Space Biochemistry Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | | | - Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin, Madison, Wisconsin, USA
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YOSHIMURA Y, ENYA K, KOBAYASHI K, SASAKI S, YAMAGISHI A. Life Explorations for Biosignatures in Space. BUNSEKI KAGAKU 2021. [DOI: 10.2116/bunsekikagaku.70.309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yoshitaka YOSHIMURA
- Department of Advanced Food Sciences, College of Agriculture, Tamagawa University
| | - Keigo ENYA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
| | - Kensei KOBAYASHI
- Graduate School of Engineering Science, Yokohama National University
| | - Satoshi SASAKI
- School of Bioscience and Biotechnology, Tokyo University of Technology
| | - Akihiko YAMAGISHI
- Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences
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Venus Atmospheric Dynamics at Two Altitudes: Akatsuki and Venus Express Cloud Tracking, Ground-Based Doppler Observations and Comparison with Modelling. ATMOSPHERE 2021. [DOI: 10.3390/atmos12040506] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present new results of our studies of zonal and meridional winds in both hemispheres of Venus, using ground- and space-based coordinated observations. The results obtained from telescope observations were retrieved with a Doppler velocimetry method. The wind velocities retrieved from space used an improved cloud-tracked technique based on the phase correlation between images. We present evidence that the altitude level sensed by our Doppler velocimetry method is approximately four kilometres higher (~4 km) than that using ground-tracked winds (using 380 or 365 nm). Since we often take advantage of coordinated space and ground observations simultaneously, this altitude difference will be very relevant in order to estimate the vertical wind shear at the related heights in future observation campaigns. We also explored a previous coordinated campaign using Akatsuki observations and its Ultraviolet Imager (UVI) at 283 and 365 nm filters, which showed that cloud-tracked winds showed a difference of about 10–15 ms−1, as in the case of the comparison between the Doppler velocimetry winds and the 365 nm cloudtracked winds. The results’ comparison also strongly suggested that the cloud-tracked winds based on the 283 nm filter’s images were sensing at about the same atmospheric altitude level as the Doppler winds. The observational results were compared with the ground-to-thermosphere 3D model developed at the Laboratoire de Meteorologie Dynamique (IPSL-Venus General Circulation Model (VGCM)) and AFES-Venus General Circulation Model (GCM), at several pressure levels (and related heights). The analysis and results showed the following: (1) additional confirmation of the coherence and complementarity in the results provided by these techniques on both the spatial and temporal time scales of the two methods; (2) we noticed in the following that the results from the two different Akatsuki/UVI filters (283 and 365 nm) showed an average difference of about 10–15 ± 5 ms−1, and we suggest this may be related to SO2 atmospheric fluctuations and the particular conditions in the coordinated observing time window; (3) we present evidence indicating that, in the context of our observations, visible Doppler methods (highly self-consistent) seem to sense wind speeds at a vertical level closer to or within the range sensed by the UVI 283 nm filter images (again, in the context of our observations); (4) modelling predicted wind profiles suggests that the layers of the atmosphere of Venus sensed by the methods referred to in Point 3 differ by approximately four km in altitude (~4 ± 2 km) regarding the cloud-tracked winds retrieved using 365 or 380 nm images.
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Yamamoto M, Ikeda K, Takahashi M. Atmospheric response to high-resolution topographical and radiative forcings in a general circulation model of Venus: Time-mean structures of waves and variances. ICARUS 2021; 355:114154. [PMID: 33052146 PMCID: PMC7545273 DOI: 10.1016/j.icarus.2020.114154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 09/28/2020] [Accepted: 10/05/2020] [Indexed: 06/11/2023]
Abstract
Thermal tides, stationary waves, and general circulation are investigated using a T63 Venus general circulation model (GCM) with solar and thermal radiative transfer in the presence of high-resolution surface topography, based on time average analysis. The simulated wind and static stability are very similar to the observed ones (e.g., Horinouchi et al., 2018; Ando et al., 2020). The simulated thermal tides accelerate an equatorial superrotational flow with a speed of ~90 m s-1 around the cloud-heating maximum (~65 km). The zonal-flow acceleration rates of 0.2-0.5 m s-1 Earth day-1 are produced by both horizontal and vertical momentum fluxes at low latitudes. In the GCM simulation, strong solar heating above the cloud top (>69 km) and infrared heating around the cloud bottom (~50 km) modify the vertical structures of thermal tides and their vertical momentum fluxes, which accelerate zonal flow at 103 Pa (~75 km) and 104 Pa (~65 km) at the equator and around 103 Pa at high latitudes. Below and in the cloud layer, surface topography weakens the zonal-mean zonal flow over the Aphrodite Terra and Maxwell Montes, whereas it enhances the zonal flow in the southern polar region. The high-resolution topography produces stationary fine-scale bow structures at the cloud top and locally modifies the variances in the geographical coordinates (i.e., the activity of unsteady wave components). Over the high mountains, vertical spikes of the vertical wind variance are found, indicating penetrative plumes and gravity waves. Negative momentum flux is also locally enhanced at the cloud top over the equatorial high mountains. In the solar-fixed coordinate system, the variances (i.e., the activity of waves other than thermal tides) of flow are relatively higher on the nightside than on the dayside at the cloud top. Strong dependences of the eddy heat and momentum fluxes on local time are predominant. The local-time variation of the vertical eddy momentum flux is produced by both thermal tides and solar-related, small-scale gravity waves.
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Affiliation(s)
- Masaru Yamamoto
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
| | - Kohei Ikeda
- National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
| | - Masaaki Takahashi
- National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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Horinouchi T, Hayashi YY, Watanabe S, Yamada M, Yamazaki A, Kouyama T, Taguchi M, Fukuhara T, Takagi M, Ogohara K, Murakami SY, Peralta J, Limaye SS, Imamura T, Nakamura M, Sato TM, Satoh T. How waves and turbulence maintain the super-rotation of Venus' atmosphere. Science 2020; 368:405-409. [PMID: 32327594 DOI: 10.1126/science.aaz4439] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/27/2020] [Indexed: 11/02/2022]
Abstract
Venus has a thick atmosphere that rotates 60 times as fast as the surface, a phenomenon known as super-rotation. We use data obtained from the orbiting Akatsuki spacecraft to investigate how the super-rotation is maintained in the cloud layer, where the rotation speed is highest. A thermally induced latitudinal-vertical circulation acts to homogenize the distribution of the angular momentum around the rotational axis. Maintaining the super-rotation requires this to be counteracted by atmospheric waves and turbulence. Among those effects, thermal tides transport the angular momentum, which maintains the rotation peak, near the cloud top at low latitudes. Other planetary-scale waves and large-scale turbulence act in the opposite direction. We suggest that hydrodynamic instabilities adjust the angular-momentum distribution at mid-latitudes.
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Affiliation(s)
- Takeshi Horinouchi
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan. .,Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Yoshi-Yuki Hayashi
- Department of Planetology and Center for Planetary Science, Kobe University, Kobe, Japan
| | - Shigeto Watanabe
- Space Information Center, Hokkaido Information University, Ebetsu, Japan
| | - Manabu Yamada
- Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Japan
| | - Atsushi Yamazaki
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Toru Kouyama
- Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | | | | | | | - Kazunori Ogohara
- School of Engineering, University of Shiga Prefecture, Hikone, Japan
| | - Shin-Ya Murakami
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Javier Peralta
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Takeshi Imamura
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
| | - Masato Nakamura
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.,Department of Space and Astronautical Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Tokyo, Japan
| | - Takao M Sato
- Space Information Center, Hokkaido Information University, Ebetsu, Japan
| | - Takehiko Satoh
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.,Department of Space and Astronautical Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Tokyo, Japan
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Thermal structure of the Venusian atmosphere from the sub-cloud region to the mesosphere as observed by radio occultation. Sci Rep 2020; 10:3448. [PMID: 32103048 PMCID: PMC7044293 DOI: 10.1038/s41598-020-59278-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 01/27/2020] [Indexed: 12/02/2022] Open
Abstract
We present distributions of the zonal-mean temperature and static stability in the Venusian atmosphere obtained from Venus Express and Akatsuki radio occultation profiles penetrating down to an altitude of 40 km. At latitudes equatorward of 75°, static stability derived from the observed temperature profiles is consistent with previous in-situ measurements in that there is a low-stability layer at altitudes of 50–58 km and highly and moderately stratified layers above 58 km and below 50 km, respectively. Meanwhile, at latitudes poleward of 75°, a low-stability layer extends down to 42 km, which has been unreported in analyses of previous measurements. The deep low-stability layer in the polar region cannot be explained by vertical convection in the middle/lower cloud layer, and the present result thus introduces new constraints on the dynamics of the sub-cloud atmosphere. The Venusian atmosphere is in striking contrast to the Earth’s troposphere, which generally has a deeper low-stability layer at low latitudes than at mid- and high latitudes.
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Long-term Variations of Venus’s 365 nm Albedo Observed by Venus Express, Akatsuki, MESSENGER, and the Hubble Space Telescope. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-3881/ab3120] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Limaye SS, Mogul R, Smith DJ, Ansari AH, Słowik GP, Vaishampayan P. Venus' Spectral Signatures and the Potential for Life in the Clouds. ASTROBIOLOGY 2018; 18:1181-1198. [PMID: 29600875 PMCID: PMC6150942 DOI: 10.1089/ast.2017.1783] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/11/2018] [Indexed: 05/17/2023]
Abstract
The lower cloud layer of Venus (47.5-50.5 km) is an exceptional target for exploration due to the favorable conditions for microbial life, including moderate temperatures and pressures (∼60°C and 1 atm), and the presence of micron-sized sulfuric acid aerosols. Nearly a century after the ultraviolet (UV) contrasts of Venus' cloud layer were discovered with Earth-based photographs, the substances and mechanisms responsible for the changes in Venus' contrasts and albedo are still unknown. While current models include sulfur dioxide and iron chloride as the UV absorbers, the temporal and spatial changes in contrasts, and albedo, between 330 and 500 nm, remain to be fully explained. Within this context, we present a discussion regarding the potential for microorganisms to survive in Venus' lower clouds and contribute to the observed bulk spectra. In this article, we provide an overview of relevant Venus observations, compare the spectral and physical properties of Venus' clouds to terrestrial biological materials, review the potential for an iron- and sulfur-centered metabolism in the clouds, discuss conceivable mechanisms of transport from the surface toward a more habitable zone in the clouds, and identify spectral and biological experiments that could measure the habitability of Venus' clouds and terrestrial analogues. Together, our lines of reasoning suggest that particles in Venus' lower clouds contain sufficient mass balance to harbor microorganisms, water, and solutes, and potentially sufficient biomass to be detected by optical methods. As such, the comparisons presented in this article warrant further investigations into the prospect of biosignatures in Venus' clouds.
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Affiliation(s)
- Sanjay S. Limaye
- Space Science and Engineering Center, University of Wisconsin, Madison, Wisconsin
| | - Rakesh Mogul
- Chemistry and Biochemistry Department, California State Polytechnic University, Pomona, Pomona, California
| | - David J. Smith
- Space Biosciences Research Branch, NASA Ames Research Center, Moffett Field, California
| | - Arif H. Ansari
- Precambrian Palaeobotany Laboratory, Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | | | - Parag Vaishampayan
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
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Yamazaki A, Yamada M, Lee YJ, Watanabe S, Horinouchi T, Murakami SY, Kouyama T, Ogohara K, Imamura T, Sato TM, Yamamoto Y, Fukuhara T, Ando H, Sugiyama KI, Takagi S, Kashimura H, Ohtsuki S, Hirata N, Hashimoto GL, Suzuki M, Hirose C, Ueno M, Satoh T, Abe T, Ishii N, Nakamura M. Ultraviolet imager on Venus orbiter Akatsuki and its initial results. EARTH, PLANETS, AND SPACE : EPS 2018; 70:23. [PMID: 31983883 PMCID: PMC6954016 DOI: 10.1186/s40623-017-0772-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 12/25/2017] [Indexed: 05/28/2023]
Abstract
The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2 and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2 and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing.
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Affiliation(s)
- Atsushi Yamazaki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Manabu Yamada
- Planetary Exploration Research Center (PERC), Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 Japan
| | - Yeon Joo Lee
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
- Present Address: Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 Japan
| | - Shigeto Watanabe
- Hokkaido Information University, 59-2 Nishinopporo, Ebetsu, Hokkaido 069-8585 Japan
| | - Takeshi Horinouchi
- Faculty of Environmental Earth Science, Hokkaido University, N10W5, Sapporo, Hokkaido 060-0810 Japan
| | - Shin-ya Murakami
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Toru Kouyama
- Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, 2-3-26 Aomi, Koto-ku, Tokyo, 135-0064 Japan
| | - Kazunori Ogohara
- School of Engineering, University of Shiga Prefecture, 2500 Hassaka-cho, Hikone, Shiga 522-8533 Japan
| | - Takeshi Imamura
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 Japan
| | - Takao M. Sato
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Yukio Yamamoto
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Tetsuya Fukuhara
- Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501 Japan
| | - Hiroki Ando
- Faculty of Science, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto, Kyoto 603-8555 Japan
| | - Ko-ichiro Sugiyama
- Department of Information Engineering, National Institute of Technology, Matsue College, 14-4 Nishi-Ikuma, Matsue, Shimane 690-8518 Japan
| | - Seiko Takagi
- Research and Information Center, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 Japan
- Present Address: Hokkaido University, N10W5, Sapporo, Hokkaido 060-0810 Japan
| | - Hiroki Kashimura
- Department of Planetology/Center for Planetary Science, Kobe University, 7-1-48, Minamimachi, Minatojima Chuo-ku, Kobe, 650-0047 Japan
| | - Shoko Ohtsuki
- School of Commerce, Senshu University, 2-1-1 Higashimita, Tama-ku, Kawasaki, Kabagawa 214-8580 Japan
| | - Naru Hirata
- School of Computer Science and Engineering, The University of Aizu, 90 Kami-Iawase, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 Japan
| | - George L. Hashimoto
- Department of Earth Science, Okayama University, 3-1-1 Tsushimanaka, Kita, Okayama 700-8530 Japan
| | - Makoto Suzuki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Chikako Hirose
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Munetaka Ueno
- Center for Planetary Science (CPS), Graduate School of Science, Kobe University, 7-1-48 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047 Japan
| | - Takehiko Satoh
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
- Department of Space and Astronautical Science, School of Physical Sciences, SOKENDAI, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Takumi Abe
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
- Department of Space and Astronautical Science, School of Physical Sciences, SOKENDAI, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Nobuaki Ishii
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
| | - Masato Nakamura
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 Japan
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Limaye SS, Watanabe S, Yamazaki A, Yamada M, Satoh T, Sato TM, Nakamura M, Taguchi M, Fukuhara T, Imamura T, Kouyama T, Lee YJ, Horinouchi T, Peralta J, Iwagami N, Hashimoto GL, Takagi S, Ohtsuki S, Murakami SY, Yamamoto Y, Ogohara K, Ando H, Sugiyama KI, Ishii N, Abe T, Hirose C, Suzuki M, Hirata N, Young EF, Ocampo AC. Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images. EARTH, PLANETS, AND SPACE : EPS 2018; 70:24. [PMID: 31983884 PMCID: PMC6954018 DOI: 10.1186/s40623-018-0789-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 01/24/2018] [Indexed: 05/28/2023]
Abstract
Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths from ultraviolet (283 and 365 nm) and near infrared (0.9-2.3 µm), to the thermal infrared (8-12 µm) from a near-equatorial orbit. The Venus Express and Pioneer Venus Orbiter missions have also monitored the planet for long periods but from polar or near-polar orbits. The wavelength coverage and views of the planet also differ for all three missions. In reflected light, the images reveal features seen near the cloud tops (~ 70 km altitude), whereas in the near-infrared images of the nightside, features seen are at mid- to lower cloud levels (~ 48-60 km altitude). The dayside cloud cover imaged at the ultraviolet wavelengths shows morphologies similar to what was observed from Mariner 10, Pioneer Venus, Galileo, Venus Express and MESSENGER. The daytime images at 0.9 and 2.02 µm also reveal some interesting features which bear similarity to the ultraviolet images. The nighttime images at 1.74, 2.26 and 2.32 µm and at 8-12 µm reveal features not seen before and show new details of the nightside including narrow wavy ribbons, curved string-like features, long-scale waves, long dark streaks, isolated bright spots, sharp boundaries and even mesoscale vortices. Some features previously seen such as circum-equatorial belts (CEBs) and occasional areal brightenings at ultraviolet (seen in Venus Express observations) of the cloud cover at ultraviolet wavelengths have not been observed thus far. Evidence for the hemispheric vortex organization of the global circulation can be seen at all wavelengths on the day- and nightsides. Akatsuki images reveal new and puzzling morphology of the complex nightside cloud cover. The cloud morphologies provide some clues to the processes occurring in the atmosphere and are thus, a key diagnostic tool when quantitative dynamical analysis is not feasible due to insufficient information.
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Affiliation(s)
- Sanjay S. Limaye
- Space Science and Engineering Center, University of Wisconsin, Madison, WI 53706 USA
| | - Shigeto Watanabe
- Space Information Center, Hokkaido Information University, Ebetsu, Hokkaido 069-8585 Japan
| | - Atsushi Yamazaki
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Manabu Yamada
- Planetary Exploration Research Center, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 Japan
| | - Takehiko Satoh
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Takao M. Sato
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Masato Nakamura
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Makoto Taguchi
- College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501 Japan
| | - Tetsuya Fukuhara
- College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501 Japan
| | - Takeshi Imamura
- Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, Kiban-tou 4H7, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 Japan
| | - Toru Kouyama
- Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | - Yeon Joo Lee
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
- Present Address: Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, Kiban-tou 4E5, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 Japan
| | - Takeshi Horinouchi
- Faculty of Environmental Earth Science, Hokkaido University, N10W5, Sapporo, Hokkaido 060-0810 Japan
| | - Javier Peralta
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Naomoto Iwagami
- School of Commerce, Senshu University, 2-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8580 Japan
| | - George L. Hashimoto
- Department of Earth Sciences, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530 Japan
| | - Seiko Takagi
- Tokai University, Research and Information Center, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 Japan
| | - Shoko Ohtsuki
- School of Commerce, Senshu University, 2-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8580 Japan
| | - Shin-ya Murakami
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Yukio Yamamoto
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Kazunori Ogohara
- School of Engineering, University of Shiga Prefecture, Hikone, Japan
| | - Hiroki Ando
- Faculty of Science, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto-City, 603-8555 Japan
| | - Ko-ichiro Sugiyama
- Department of Information Engineering, National Institute of Technology, Matsue College, 14-4 Nishi-Ikuma, Matsue, Shimane 690-8518 Japan
| | - Nobuaki Ishii
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Takumi Abe
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Chikako Hirose
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Makoto Suzuki
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210 Japan
| | - Naru Hirata
- ARC-Space, CAIST, The University of Aizu, 90 Kami-Iawase, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 Japan
| | - Eliot F. Young
- Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302 USA
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Scattering Properties of the Venusian Clouds Observed by the UV Imager on boardAkatsuki. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-3881/aa78a5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Reale F, Gambino AF, Micela G, Maggio A, Widemann T, Piccioni G. Using the transit of Venus to probe the upper planetary atmosphere. Nat Commun 2015; 6:7563. [PMID: 26102562 PMCID: PMC4557371 DOI: 10.1038/ncomms8563] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 05/19/2015] [Indexed: 11/16/2022] Open
Abstract
During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80 km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70 km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena. The atmosphere of a transiting planet shields the stellar radiation enabling size and density stratification to be estimated. Here, the authors study Venus and show that the measured radius depends on the wavelength used, which has implications for Venus's ionosphere and may help in planning future missions.
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Affiliation(s)
- Fabio Reale
- 1] Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, Palermo 90134, Italy [2] INAF/Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, Palermo 90134, Italy
| | - Angelo F Gambino
- Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, Palermo 90134, Italy
| | - Giuseppina Micela
- INAF/Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, Palermo 90134, Italy
| | - Antonio Maggio
- INAF/Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, Palermo 90134, Italy
| | - Thomas Widemann
- Universitè de Versailles-Saint-Quentin, ESR/DYPAC EA 2449, Observatoire de Paris, LESIA, UMR CNRS 8109, 5 Place Jules-Janssen, Meudon 92190, France
| | - Giuseppe Piccioni
- INAF-IAPS (Istituto di Astrofisica e Planetologia Spaziali), via del Fosso del Cavaliere 100, Roma 00133, Italy
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Misra A, Krissansen-Totton J, Koehler MC, Sholes S. Transient Sulfate Aerosols as a Signature of Exoplanet Volcanism. ASTROBIOLOGY 2015; 15:462-477. [PMID: 26053611 DOI: 10.1089/ast.2014.1204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Geological activity is thought to be important for the origin of life and for maintaining planetary habitability. We show that transient sulfate aerosols could be a signature of exoplanet volcanism and therefore of a geologically active world. A detection of transient aerosols, if linked to volcanism, could thus aid in habitability evaluations of the exoplanet. On Earth, subduction-induced explosive eruptions inject SO2 directly into the stratosphere, leading to the formation of sulfate aerosols with lifetimes of months to years. We demonstrate that the rapid increase and gradual decrease in sulfate aerosol loading associated with these eruptions may be detectable in transit transmission spectra with future large-aperture telescopes, such as the James Webb Space Telescope (JWST) and European Extremely Large Telescope (E-ELT), for a planetary system at a distance of 10 pc, assuming an Earth-like atmosphere, bulk composition, and size. Specifically, we find that a signal-to-noise ratio of 12.1 and 7.1 could be achieved with E-ELT (assuming photon-limited noise) for an Earth analogue orbiting a Sun-like star and M5V star, respectively, even without multiple transits binned together. We propose that the detection of this transient signal would strongly suggest an exoplanet volcanic eruption, if potential false positives such as dust storms or bolide impacts can be ruled out. Furthermore, because scenarios exist in which O2 can form abiotically in the absence of volcanic activity, a detection of transient aerosols that can be linked to volcanism, along with a detection of O2, would be a more robust biosignature than O2 alone.
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Affiliation(s)
- Amit Misra
- 1 Department of Astronomy, University of Washington , Seattle, Washington
- 2 University of Washington Astrobiology Program, University of Washington , Seattle, Washington
| | - Joshua Krissansen-Totton
- 2 University of Washington Astrobiology Program, University of Washington , Seattle, Washington
- 3 Department of Earth and Space Sciences, University of Washington , Seattle, Washington
| | - Matthew C Koehler
- 2 University of Washington Astrobiology Program, University of Washington , Seattle, Washington
- 3 Department of Earth and Space Sciences, University of Washington , Seattle, Washington
| | - Steven Sholes
- 2 University of Washington Astrobiology Program, University of Washington , Seattle, Washington
- 3 Department of Earth and Space Sciences, University of Washington , Seattle, Washington
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16
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Misra A, Meadows V, Claire M, Crisp D. Using dimers to measure biosignatures and atmospheric pressure for terrestrial exoplanets. ASTROBIOLOGY 2014; 14:67-86. [PMID: 24432758 PMCID: PMC3928785 DOI: 10.1089/ast.2013.0990] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 μm dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bar and for O2 volume mixing ratios above 50% of Earth's present-day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 μm and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We also performed detectability studies for JWST transit transmission spectroscopy and found that the 1.06 and 1.27 μm dimer features could be detectable (SNR>3) for an Earth analogue orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis. We calculated the required signal-to-noise ratios to detect and characterize O2 monomer and dimer features in direct imaging-reflected spectra and found that signal-to-noise ratios greater than 10 at a spectral resolving power of R=100 would be required.
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Affiliation(s)
- Amit Misra
- University of Washington Astronomy Department, Seattle, Washington, USA
- NAI Virtual Planetary Laboratory, Seattle, Washington, USA
- University of Washington Astrobiology Program, Seattle, Washington, USA
| | - Victoria Meadows
- University of Washington Astronomy Department, Seattle, Washington, USA
- NAI Virtual Planetary Laboratory, Seattle, Washington, USA
- University of Washington Astrobiology Program, Seattle, Washington, USA
| | - Mark Claire
- NAI Virtual Planetary Laboratory, Seattle, Washington, USA
- Department of Earth and Environmental Sciences, University of St Andrews, Fife, Scotland
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Dave Crisp
- NAI Virtual Planetary Laboratory, Seattle, Washington, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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17
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Luz D, Berry DL, Piccioni G, Drossart P, Politi R, Wilson CF, Erard S, Nuccilli F. Venus’s Southern Polar Vortex Reveals Precessing Circulation. Science 2011; 332:577-80. [DOI: 10.1126/science.1201629] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- D. Luz
- Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, 1349-018 Lisboa, Portugal
| | - D. L. Berry
- Departamento de Física, Universidade de Évora, 7002-554 Évora, Portugal
| | - G. Piccioni
- Istituto Nazionale di Astrofisica, Istituto Nazionale di Astrofisica– Istituto di Astrofisica Spaziale e Fisica Cosmica (INAF-IASF) Rome, 00133 Rome, Italy
| | - P. Drossart
- Laboratoire d’Études Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris-Diderot, F-92195 Meudon Cedex, France
| | - R. Politi
- Istituto Nazionale di Astrofisica, Istituto Nazionale di Astrofisica– Istituto di Astrofisica Spaziale e Fisica Cosmica (INAF-IASF) Rome, 00133 Rome, Italy
| | - C. F. Wilson
- Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - S. Erard
- Laboratoire d’Études Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris-Diderot, F-92195 Meudon Cedex, France
| | - F. Nuccilli
- INAF–Istituto di Fisica dello Spazio Interplanetario (IFSI) Rome, 00133 Rome, Italy
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